The present invention relates to a document feeder for feeding an original from a sheet feed stacker to an image reading platen in an image input device such as a copy machine, a printer, a scanner, and a facsimile machine, and storing the originals on a sheet discharge stacker. The present invention also relates to an image reading apparatus with the document feeder.
In general, there have been various feeding devices for automatically feeding and placing an original from a sheet feed stacker to an image reading platen in a scanner. A conventional feeding device is mounted on an upper portion of the platen of the image reading apparatus using the hinge so that the feeding device can be freely opened and closed. When the feeding device is not used for reading an original, an operator opens the feeding device to place the original on the platen manually and then covers the platen with the feeding device.
Recently, a copy machine, a scanner, and the like have been connected to a computer system in a network for reading images for a variety of purposes. For example, there has been a growing need for automatically feeding a special original, e.g., a photograph, negative film, and OHP (overhead projector) sheet, to a platen for reading with a feeding device. It is preferable that an operator can easily mount and remove such a device in use. Accordingly, it is required to make the device compact and light.
Japanese Patent Publication (Kokai) No. 62-126044 has disclosed a compact device in which transporting means is disposed above a platen, and a sheet feed stacker and a discharge stacker are arranged in parallel vertically above the transporting means. An original is transported from the sheet feed stacker through a U-shaped path and returned to the discharge stacker through the U-shaped path. In the device, it is difficult to transport a photograph, OHP sheet, and the like through the curved route, i.e. the U-shaped path, without damaging. The device has a relatively large height over the platen, thereby making the device unstable upon installing and dismounting.
Japanese Patent Publication (Koukoku) No. 05-47816 has disclosed a device in which a transport belt is disposed above a platen for transporting an original from a stacker located at a lower side. In this case, it is difficult to easily mount and dismount the entire unit above the platen. Further, in the device, the discharge stacker is located above the sheet feed stacker. An original is transported from the sheet feed stacker along the platen, and switched back and discharged from the platen to the discharge stacker. Accordingly, it is necessary to dispose the sheet feed stacker and discharge stacker in a vertical space as small as possible. When the discharge stacker is disposed above the sheet feed stacker in a small space, it is difficult to set originals on the sheet feed stacker at a proper position.
Japanese Utility Model (Koukoku) No. 59-7316 has disclosed a device in which a discharge stacker is rotatably mounted on a frame at an upper position, so that the discharge stacker is lifted to extend a space above a sheet feed stacker when an original is placed. In the device, the discharge stacker is disposed above the sheet feed stacker. A forward end of the discharge stacker in the feeding direction is supported on the frame, and a rear end of the discharge stacker is rotatable vertically. When sheets are stored on the sheet feed stacker, the discharge stacker is rotated upwardly, thereby making it easy to place the sheets.
In the device in which the transporting means, sheet feeding and discharging stackers are arranged above the platen of a scanner, etc., or the sheet feeding and discharging stackers are arranged at a side of the platen, and the originals are transported to the transporting means above the platen, it is still difficult to mount and dismount the device above the platen. Also, it is difficult to provide a transporting mechanism such as a vacuum fan for a special original such as a photograph above the platen due to a spatial limitation.
As described above, in the device disclosed in Japanese Utility Model Publication (Koukoku) No. 59-7316, the discharge stacker is rotatable to extend a space between the sheet feed stacker and the rear end of the discharge stacker when an original is placed on the sheet feed stacker. However, a space between the sheet feed stacker and the forward end of the discharge stacker is narrow (forward end in the feeding direction). Accordingly, when the original is inserted, the original is rubbed and may be damaged. Especially in a case that the original like a photograph has a surface coated with a soft material such as gelatin, when a bundle of the originals is inserted into the wedge-shaped forward end of the stacker, the originals contact against with each other and may be damaged or the uppermost sheet of the originals is damaged by a paper feed roller.
Therefore, in the device disclosed in Japanese Utility Model Publication (Koukoku) No. 59-7316, in which the space at the rear end of the stacker is widened, it is still difficult to place the originals on the sheet feed stacker at a right position without causing damage. It is possible that the originals are transported with forward end damaged or bent, thereby causing paper jam.
In view of the problems described above, the present invention has been made, and an object of the invention is to provide a feeding device capable of reliably transporting an original from a sheet feed stacker along a platen, and an image reading apparatus provided with the feeding device. The feeding device has a unit structure of a sheet feed stacker, a sheet discharging stacker and transporting means, so that it is easy to mount and remove the unit structure above the platen. Also, the feeding device can feed and discharge a special original such as a photograph and OHP sheet.
Another object of the invention is to provide a feeding device with a simple structure, in which it is easy to place a bundle of originals in a proper posture on the sheet feed stacker arranged below the discharge stacker in parallel. It is possible to easily insert a forward end of the original between a feeding member such as a paper feed roller and a bottom surface of the stacker without damage. It is also possible to feed and discharge a susceptible original such as a photograph at a predetermined position on the platen. Accordingly, the originals are placed on the sheet feed stacker, and discharged to the sheet discharging stacker with little damage.
Further objects and advantages of the invention will be apparent from the following description of the invention.